Upgrade from asterisk 1.2 to 1.6

Hi all , I have a problems with asterisk 1.6.
I have this custum rules :

[ext-local-custom]
exten => 25,1,ChanIsAvail(Sip/307,s)
exten => 25,2,ChanIsAvail(Sip/308,s)
exten => 25,3,Macro(user-callerid)
exten => 25,4,Dial(Sip/307&Sip/308,180,)
exten => 25,5,Playtones(busy)
exten => 25,6,wait(5)
exten => 25,7,Hangup()
exten => 25,102,NoOP
exten => 25,103,Playtones(busy)
exten => 25,104,wait(5)
exten => 25,105,Hangup()

On asterisk 1.2 and 1.4 this rules works fine . If I was on the phone 307 and someone call 25 the 308 doesn't ring.
If I put this extension custom rules on asterisk 1.6 , the rules doesn't work.I was on the phone 307 and someone call 25 , the second phone 308 rung.
Can you help me ?
Oscar